Field of the Invention
The present embodiments relate to an organic light emitting diode display device, and more particularly, to an organic light emitting diode display device capable of reducing the reflectance thereof and realizing a clear black color.
Description of the Related Art
With progress to the information-oriented society, various demands for display devices for displaying an image are increasing. Recently, various kinds of flat panel display devices such as a liquid crystal display (LCD) device, a plasma display panel (PDP) device, and an organic light emitting diode (OLED) display device have been used.
Of the above-described display devices, an OLED display device can be manufactured in a lightweight and thin form since it uses a self-light emitting element and thus does not need a backlight used for a liquid crystal display (LCD) device using a non-emitting element. Further, the OLED display device is excellent in viewing angle and contrast ratio and advantageous in terms of power consumption as compared with the LCD device. In addition, the OLED display device can be driven with a low DC voltage and has a high response speed and includes internal components in the form of solids. Therefore, the OLED display device has the advantages of a high resistance to external shocks, a wide category temperature range, and particularly, low manufacturing costs.
Such an OLED display device displays an image in a top-emission manner or a bottom-emission manner depending on a structure of an organic light emitting element including a first electrode, a second electrode, and an organic light emitting layer. In a bottom-emission OLED display device, a visible light generated from the organic light emitting layer is displayed on a bottom side of a substrate on which a TFT is formed. Further, in a top-emission OLED display device, a visible light generated from the organic light emitting layer is displayed on a top side of the substrate on which the TFT is formed.
Meanwhile, the OLED display device includes a polarizing plate including a circular polarizing plate and a linear polarizing plate, which realizes black for the OLED display device and reduces external light reflection so as to improve visibility. However, using the polarizing plate in the OLED display device is costly and reduces the brightness of the OLED display device.
Therefore, the polarizing plate disposed on or under a display panel is removed and a transmittance control film is applied. However, the reflectance of the display panel is increased and the transmittance of the transmittance control film is decreased, which reduces the light efficiency. Particularly, in an OLED display device including a white (W) sub-pixel, the white (W) sub-pixel without a color filter layer has far higher reflectance than red (R), green (G), and blue (B) sub-pixels, which have a color filter layer. Further, the color filter layers disposed in the red (R), green (G), and blue (B) sub-pixels cause deterioration in visual sensation of a black color in the OLED display device. Accordingly, an OLED display device capable of solving this problem has been demanded.